Who makes the highest quality tube amps?

All tube OTL amplifiers use SEPP, cyclotron or Mr. Futterman’s variations. All these are push-pull amplification stages. They can claim single ended, but they are push pull topologies. Feedback is mandatory in this designs to cancel out the artifacts generated by the problems of not true complimentary driving of the signal, and of course cross-over distortion. Some clever variations have been presented on the market during recent years, but they are nevertheless push pull topologies with many dbs of negative feedback, some of them use up to 60db of degenerative feedback. Of course, these amplifiers are not Class A devices.

@believehifi Just so you know, the statements in the post above are mostly false. Here's why:
There are in fact single-ended OTLs (which don't make much power) and they are **not** push pull. Here's one:https://www.transcendentsound.com/mini-beast.html

We don't use feedback in most of our amps (MA-1, MA-2 and MA-3) and those that do use it run only 2-4 db. Even then we have customers that have us add a switch so they can switch it out which is no problem. We rely on other methods to minimize distortion; this is in order to keep higher ordered harmonics at bay because the ear is so sensitive to higher ordered harmonics.

I can't speak for others, but in our case we have a completely symmetrical design and don't have the need for complementary output devices. We do that through the use of the Circlotron, and were the first manufacturer to use that circuit after EV discontinued its use in the 1950s. For several decades we were the *only* manufacturer using it.

60 db of 'degenerative feedback' sounds impossible to me (I suspect you are referring to loop feedback??). Can you provide a link? And finally, we can and do build our amps to be class A (A2, to be specific). The class of operation is somewhat load specific; a higher load impedance is needed on the smaller amps to remain in the class A region. We don't have crossover distortion problems since we don't employ an output transformer and we paid special attention to making sure that every part of the amp (voltage amplifier, driver and output section; there is no dedicated phase splitter) have operating points that simply prevent any sort of crossover issue. As a result, distortion linearly decreases to unmeasurable as the power level is decreased. Usually the only kind of amp that can do that is single-ended.

I own Dyna. I go with Dyna. So did old man Johnson of ARC, who copied Dyna. (RIP) And others.

Bill Johnson modified Dynaco amps (the ST-70 that ARC had on display in their museum was recently sold) but he didn't copy them (the ARC ST-70 used a driver circuit that had a lot of balanced circuits in it).  He did also use the Dynaco output transformer in the D-50, D-51, D-75 and a few others, which adds to the confusion.

I currently own the Bob Carver Raven 350 amps. They replaced a Atma-Sphere M-60 Mk3.3 and before that Pass Labs X350 amps.

The newest Carver amps are really quite special. They are all made by hand, hard wired and made one at a time per order.

ozzy

ozzy"The newest Carver amps are really quite special."

Does that mean that your's haven't caught on fire yet?

How the "F" do you measure "highest quality"? By the quality of the parts? By the quality of the assembly? Performance? Durability? How about versatility with different types of loudspeakers? How about the longevity of the manufacturer and customer service? These all make sense, but then what about these qualities relative to price? Or is price not a factor? What if I asked you "who makes the highest quality sedans?" Or, "who makes the highest quality watches?". I truly hate to be negative, but your question is simply stupid. You might as well ask "who makes the best sounding tube amps that are also durable"? And guess what? Even with that more narrow question, all you would get here is a list of names of what people on this Board own. 'Cause that's the way this Board works. Now I don't mean to be a complete ass, so I would express the opinion that for most tube amps, the quality of the transformers is incredibly important but so is everything else. Point to point wiring is nice too, but not always practical. You got some very good names. You can't go wrong with Manley, VTL, Atma-Sphere, Coincident, C-J, Quicksilver, and for the most part (smiley-they have had a dud or two), ARC. The big names got to be big names for a reason. You have to live with your choice so rather than take a poll of worthless opinions, take a look at the aesthetics and listen. I happen to think that more-so than with SS, tube amps often have distinctive appearances. I don't care how good they sound, I don't care for the looks of Quicksilver (those hose clamps holding down large capacitors just make me itch) or Coincident. A tube amp sticks out like a sore thumb (perhaps a poor choice of words) in any listening room, so pick out one that not only floats your aural boat, but that you also don't mind looking at. That's just my opinion. When Pathos first came out with their amps and when Manley first came out with the Stingray, I was smitten, but I am glad I never bought either. Sound has to come first. I am not saying they sound bad, but I believe there are better sounding tube amps out there that those two. 

Lets go with highest quality being equated to longevity.  Without any way of providing proof, I have to think that the Dynaco ST-70's have the most longest lived tube amps still in circulation.  I still think they sound passable.